Hi, 7 point, welcome to the Lawrence Welk crowd. Congrats on getting serious.
No idea if lukemia affects muscle building, but bear in mind people vary naturally for a variety of reasons. Also, at our age, it's challenging for all of us.
ditto on Paleo. It's strict, but helps carve off the fat and gets you tough. Here's all the links you could ever need: http://paleodiet.com/
Free weight exercises, like deadlifts and presses, are definitely the way to push the strength up. You're already doing physical labor, that's good.